Lapping machine



Aug. 9, 1932. H. s. INDGE 1,870,328

LAPPING MACHINE Filed July 21. 1930 s Sheets Sheet 1 W/T/VES-SESiNVENTOR W HERBERT 61mm:

W L. BY QQ V ATTO EY Aug. 9, 1932. H. s. INDGE 1,870,328

LAPPING MACHINE Filed July 21. 1930 3 Sheets-Sheet 2 III INVENTORWITNESSES HERBERTS. //v0c;

H. S. INDGE Aug. 9, 1932.

LAPPING MACHINE Filed July 21, 1930 3 Sheets-Sheet ENVENTO HERBERT 5.lA/DGE BY ATT NEY W/ T/VEJSES Patented Aug. 9, 1932 UNITED STATESPATENT, OFFICE HERBERT S. INDGE, OF WESTBORO, MASSACHUSETTS, ASSIGNOR TONORTON COMPANY F WORCESTER, MASSACHUSETTS, A CORPORATION OFMASSACHUSETTS LAIPPING MACHINE Application filed July 21, 1930. SerialNo. 469,367.

This invention relates to that type of grinding machinery commonly knownas lapping machines and especially to a machine adapted tosimultaneously and precisely lap duplicate surfaces on a multiplicity ofsimilar work pieces which may be either flat or cylindrical in shape.

A machine of this general type has been utilized heretofore for lappingeither the IQ parallel fiat surfaces of such articles as piston rings,metal disks and the like, or articles of cylindrical shape, such asautomotive wrist pins as well as similar articles which require -a highfinish within extremely narrow limits of accuracy. In such machines, amultiplicity of duplicate work pieces are placed within a workpositioning or work retaining cage which guides them through a combinedrotating, sliding and eccentric break-up mog tion while in engagementwith the two opposed metal laps charged with abrasive, one

or both of which may be fixed against rotation. It has often been thepractice in such machines to rotate the lower lap and the work cage atdifferent rates of speed and to permit the upper lap to .rest uponthework by the force of gravity. Owing to the increased popularity oflapped automotive arts and the exacting demands of the machine industryfor accurately finished moving parts, this type of lapping machine hasbeen found too slow in its operation and consequently expensive to use.The metal laps frequently lose their form and have to be removed fromthe machine for a truing and recharging operation which is expensive andinvolves considerable loss of time as well as effort on the part of theoperator.

The present invention relates to an improvement over this rior type oflapping machine and has for its primary object the provision of alapping machine in which rotating abrasive wheels are used to lap amultiplicity of duplicate work pieces with extreme precision and greatrapidity, and in which the work pieces are moved through a constantlychanging path relative to the two rotating wheels and the rates ofmovement are such that the operative surface of each lap may be utilizedefliciently and the abrading.

action imparted to the Work by each lap will be substantially identical.

With this and other objects in view, as will be apparent to one skilledin the art, this invention resides in the features set forth in thespecification and covered by the appended claims.

In accordance with this invention, I have provided a lapping machinehaving two opposed abrasive laps, and' preferably wheels of bondedabrasive grains, which are rotated at different rates and preferably inopposite directions while in operative engagement with a multiplicity ofduplicate work pieces. If it is desired to lap the two opposed parallelsurfaces of a multiplicity of flat work pieces, they are mounted withina work cage which is driven through a composite motion of rotation andgyration at such a rate that the work pieces retained therein are movedthrough a progressively changing path and receive an identical lappingaction upon each of the surfaces being lapped. If it is desired to lapthe peripheral surfaces of a multiplicity of cylindrical work piecesthey are mounted .within a work cage which is so arranged that it isfreely rotatable about an eccentrically driven centering member, thuspermitting 7 the cylindrical work pieces to roll upon the lappingsurfaces at a differential speed and also imparting a sliding action ofthe work pieces between-the laps at the same time. Means are providedwhereby the irregular path of the work pieces may be controlled andadjusted to different sizes of work. The gvratory motion of the workcage isusually so regulated that each work piece comes in contact withthe entire operative surface of each of the laps before the completionof the lappingcycle, thereby causing an even wear upon the laps andmaking a truing of their operative surfaces rarely necessary.

Referring to the drawings which illustrate one embodiment of theinvention and in which like reference numerals indicate like parts: Y

Fig: 1 is a vertical elevation partly in section showing the assembledlapping machine;

. motion to the work cage.

Fig. 2 is a sectional view showing the relative position of the laps andthe work and associated driving mechanism during the lapping operationwhen the machine is adapted for flat lapping;

Fig. 3 is a fragmentary View taken approximately along the line 33 ofFig. 1;

Fig. 4 is a sectional view taken along the line 4-4 of Fig. 2;

Fig. 5 is a view similar to Fig. 3 but showing a work cage adapted tohold cylindrical work; and

Figs. 6 and 7 show the mechanism for supporting and driving a work cageadapted for cylindrical work.

Referring more particularly to the embodiment of this invention asillustrated, the lap ping machine may be constructed in its generalaspects similar to the machine disclosed in the United States patent toIndge No. 1,610,527 and this machine as herein illustrated comprises abase 10 adapted to support a lower lap 11 and an upper lap 12 betweenwhich is arranged a work guiding member or work cage 13. Both the upperand lower laps rotate, preferably in difi'erent directions. A compositemotion of rotation and gyration is imparted to the work cage whichcauses the work pieces retained therein to move through a so-calledeccentric break-up motion along a progressively changing path which maybe regulated as desired.

Power may be supplied to the machine in any convenient manner, such asby a belt arranged to rotate a pulley 15 keyed to a shaft 16 journaledin the base 10 of the machine and arranged to rotate both the upper andlower laps as well as to transmit an irregular A worm 17 is fastened tothe shaft 16 in such a position that it is constantly enmeshed with aworm wheel 19 keyed to a vertical sleeve 20 rotatably supported bybearings 22 and 23 secured within a hub 25 bolted to the base of themachine. The upper end of the sleeve 20 has a tapered head 26 and aspider member 27 is accurately fitted and keyed thereto. This spidermember has a bearing surface 28 adapted to fit erractly against the topof bearing 22 and hub 25 and thereby support sleeve 20 and itsassociated parts in correct vertical position. To further secure saidsleeve in correct vertical position, a threaded portion 29 is providedthereon just below the bearing 22 and a bearing nut 30 is locked inlight contact with the under side of bearing 22 so that the sleeve willbe free to rotate without any endwise movement. A driving plate 32 isfirmly mounted upon the spider 27 and securedthere-to by bolts 33. Thelower lap 11, which is illustrated as an annulus of Ceramic bondedabrasive grains made like a grinding wheel, is firmly gripped by thedriving plate and maintained as an integral part therewith bymeans of aretaining ring 35 fastened to the driving plate by means of screws 36.Thus any rotary motion applied to pulley 15 is transmitted through shaft16 and worm 17 to worm wheel 19, sleeve 20, spider member 27 and drivingplate 32 to rotate the lower lap 11.

During rotation of the lower lap, the work cage 13 is moved through anirregular path. A gear 38 is keyed to sleeve 20 and maintained inposition just below worm wheel 19 by a nut 39 screwed onto a threadedportion 40 on the lower end of the sleeve. A cluster gear 42, rotatablymounted on a stud 43 supported within a hub 4401 the base, is constantlyin mesh with gear 38 on sleeve 20 and gear 46 which is fastened to aspindle 47 journaled within the sleeve 20 in bearings 48 and 49. At theupper end of the spindle, a head 52 is fastened so that it may rotatetherewith and within the spider member 27. The head 52 is provided withthree studs 53 equally spaced .from each other and equidistant from thespindle 47 about which they revolve. Upon each one of these three studs53 is rotatably mounted a clustergear 55, said gears being so positionedthat they are constantly in mesh with an internal ring gear 56 securedto the'spider member 27 by screws 57 as shown in Fig. 4, this spiderbeing rotated with the lower lap. Each of these three cluster gears alsois constantly in mesh with apinion 59 mounted for free rotation upon theupper end of the spindle 47. Three other studs 62 are fixedly supportedby the head 52 equidistant from each other and also equidistant from thespindle 47 about which they revolve. Gears 63 are rotatably mounted, oneupon each of the studs 62 in such positions as to be constantly in meshto rotate with pinion 59.

A casing 66 forms an integral part of the spider member 27 and providesa container for a lubricant in which the gears may rotate. A cover 67 isprovided to prevent dust and foreign matter from coming in contact withthe moving parts and thereby causing wear. A cap 69 is fastened byscrews 7 O to the hub of each one of the three gears 63 so that it willrotate concentric therewith. Each cap has several duplicate tap ed holes72 located in various positions wit in its upper face. Work cagesupporting and driving studs 73 are screwed into one of the threadedholes in each cap in corresponding posit-ions and each stud has anadjustable supporting member at its upper end arranged to position anddrive the work cage 13 between the two laps.

To adjustably support the work cage relative to the two opposed laps sothat it will not contact therewith, I provide supporting heads 76arranged to slidably fit over each one of the work cagedriving studs 73.Each ofthese supporting heads has a'flanged portion 77 arranged toengage the under side of the work cage 13 and a threaded portion 78 overwhich a nut 79 may be screwed to engage the top face of the work cage.An adjusting screw 80 is threaded into the upper portion of eachsupporting head and engages the top of each stud 7 3 respectively. Thusthe ma chine operator may turn each of these adjusting screws andaccurately position his work cage between the opposed laps and then lockthe screws in position by tightening a lock nut 81 against the top ofeach supporting head.

The work cage for fiat lapping in my preferred construction comp-rises ametal disk or plate having a multiplicity of circular holes 83 withinwhich flat workpieces 84 may be loosely retained. Three holes are alsoprovided within which the supporting heads 76 may be secured. Thus whenthe lower lap rotates, a combined motion of rotation and gyration istransmitted to the Work cage since rotation of pulley 15' transmits asimilar motion of rotation through shaft 16, worm 17 ,worm wheel 19,gears 38, 42 and '46 to rotate spindle 47 and head 52 which carries thethree work cage driving studs supported by gears 63 upon studs 62 fixedto the head 52.

During the rotation of spindle 47 and head 52 secured thereto, studs 73revolve each about its own central support or stud 62, since the geartrain comprising gears 38, 42 and 46 has been so selected that sleeve 20and spindle 47 supported therein rotate at different rates. Thisdifferent rate of'rotation causes the three cluster gears carried bystuds 53 to roll upon ring gear 56 and to transmit rotary motion to thethree gears 63 through the pinions 59 and 64 which are fastenedtogether. Studs 73 which carry the work cage rotate with gears 63 andrevolve eccentrically in synchronism about studs 62.

These studs 62 are revolved slowly about the axis of the central spindle47, and at. the same speed. Consequently, the motion of revolution ofstuds 62 is compounded with the motion of revolution of stud 73 andthereby causes the work pieces in the cage to travel with a compoundrating and revolving motion. By changing the position ofthe studs 73 theamount of eccentric motion imparted to the work cage during its rotationmay be varied for difierent'types and sizes of work.

If the operator desires to lap cylindrical work pieces, such asautomotive wrist pins and the like, this machine may be quickl andeasily adapted to accurately lap suc work, as shown in Fig. 6. Forlapping cylindrical work pieces, it has been found necessary to supportthe work cage so that it may freely andeccentrically rotate relativeto'the two opposed laps, thereby subjectingthe work pieces to a combinedrolling and sliding action between the laps for an even abrading action.To accomplish this,

I have made that one of the three studs 53 which is shown in Fig. 2 longenough to extend out through the cover 67 and through a slotted portion90 in a member 91 which is slidably mounted on Ways 93 upon cover 67. Anut 94 is screwed onto a threaded portion on the end of the elongatedstud 53 and engages the top of member 91, clamping it firmly in anypreadjusted position upon the ways 93. A threaded portion 95 is providedin one end of the member 91 so that a work cage centering stud 96 may beremovably screwed therein.

When the machine operator desires to lap cylindrical work pieces, heremoves the cage 13 adapted for flat lapping and unscrews each of thedriving studs 73, whereupon he may mount stud 96 in member 91. A workcage 13a adapted to hold a multiplicity of cylindrical work pieces 98within slotted portions 99 is rotatably mounted upon a hub 100 which isarranged to be screwed up and down a threaded portion 101 of stud 96 toadjust the work cage so that it may freely rotate between the twoopposed laps with-- A rotatable upper lap 12 of substantially V the samesize and structure as the lower lap is supported above the lowen lap bya frame 105 mounted upon the base of the machine and also supports afeeding mechanismtherefor. In order to permit rotation of the upper lapa spindle 106 is rotatably supported within the frame 105 and isprovided with a head 108 to which the upper lap is firmly secured by aretaining ring 109. The head 108 is supported and driven by ball andsocket members 110 and 111 which may be firmly secured together byscrews112 or which if loosened may be free to float within one another andtherebypermitthe upper lap to adapt itself to the upper surface of theworkpieces and freely float thereupon. Member 111 is secured to spindle106 by key 114 and nut 115 which engage member 111 through washer 116.Member 110 is firmly fastened to the head 108 by screws 118. Shaft 106is journaled in bearings 119 and 120 within sleeve 121 in the frame 105.A pulleyf 122 is slidably keyed at the upper end of spindle 106'and ismaintained in constant driving engagement with a pulley 125 keyed on theshaft 16, by a belt 126 which Y passes over idler pulleys 127.

To facilitate adjustment of the laps relative to the work, the upper lapis mounted so that it may be moved vertically toward and from the lowerlap. To accomplish this, the sleeve 121 is slidably mounted within frame105. A hand wheel 129 is secured to a shaft 130 mounted for rotationwithin bearings in the frame 105. A worm 132 is fastened upon shaft 130and so positioned that it will be constantly in mesh with a worm wheel133 which is fastened to rotate with a cross shaft 134 supported forrotation in suitable hearings in frame 105. A pinion 135 is also securedto cross shaft 134 and in such a position as to be constantly in meshwith a rack 136 out withln the face of sleeve 121. Thus rotation of thehand wheel 129 in either direction will rotate the worm 132, worm wheel133 and pinion 135 causing the upper lap to move toward or from thelower lap.

' shown as metal disks 84. are each placed within one of a plurality ofholes 83in the work cage 13. The operator then turns hand wheel 129 tolower the upper-lap 12 until it rests upon the work pieces by the forceof gravity,

' after which the machine may be placed in operation by rotating pulley15 with any suitable source of power. The studs 7 3 are so positionedwithin the various holes 72 that the eccentric travel of the work cagewill carry each workpiece across-the entire width of the two opposedannular lapping surfaces during the lapping cycle and thereby cause thelaps to wear away evenly. Each of the screws 80 is adjusted and lockedin position so that the work cage 13 will be substantially parallel tothe opposed lap surfaces and out of contact therewith.

By utilizing two rotating abrasive laps, I have found it practicable toreduce the speed of rotation of-the work cage to a relatively slow rateas compared with machines. of previous constructions. This slow rotationof the work cage permits the fast rotating abrasive lap to continuouslyand positively rotate each work piece within the work cage as it travelsalong its irregular, ever changing path and thus prevents the likelihoodof excessive or uneven wear upon either the lap or the work pieces. Inthe preferred form of my invention, as illustrated, it has been foundpracticable to rotate the lower lap at approximately 113 R. P. M. in acounter-clockwise direction and the upper lap at approximately 97 R. P.M. in a clockwise direction. The work cage is usually rotated in thedirection of thefaster lap at approximately one-half the difference ofthe two opposed laps when lapping flat work pieces. Thus the rate ofroexcessively high rate of work cage rotation tended to throw the workpieces against the side of the work cage and create sufiicient frictionto prevent the work pieces from rotating within the cage properly duringthe lapping operation. Such a condition tended to leave abrading marksupon the work pieces and to wear them away at an uneven rate, thusseriously impairing the accuracy of the work being lapped.

cylindrical work, such as automotive wrist pins and the like, thismachine may be quickly adapted to lap such work by removing the workcage 13 adapted for flat lapping and removing the cage driving pins 73,whereupon the stud 96 may be screwed into member 91 and the work cage13a adapted for cylindrical work may be mounted thereupon as illustratedin Figs. 5 and 6. Since the work cage 13a is freely rotatable upon theadjustable hub 100, it may be positioned so that the cylindrical workpieces 98 retained therein will be free to rotate at a differentialspeedbetween the two opposed laps. During the rotation of the work cage,the centering pin 96 moves it through an eccentric motion which may beeasily regulated by loosening nut 94 and sliding the member 91 on theways 93 so that each work piece will travel across the entire width ofthe two annular lapping surfaces during the lapping cycle thus causingan even wear on both laps.

Bonded abrasive laps are used in this machine, since they not onlyabrade the work at a faster rate than do the metal laps charged withabrasive as used in prior. machines, but also may be employedcontinuously until too thin for further usefulness. It is necessary totrue the lapping surfaces only when they become unevenly worn and thisrarely occurs unless the machinehas had abusive treatment.

Having thus described my invention, what I claim as new and desire tosecure by Letters Patent is:

v 1. Alapping machine comprising two opposed laps and a work cagesupported theretween, a rotatable spider arrangedto support one of thelaps, a head mounted concentric with the spider and rotatable relativethereto, means to rotate said head and spider at different ratesofspeed,pinions rotatably mounted upon said head and spaced from itsaxis so as to revolve therewith, driving pins arranged to engage saidwork cage, each of said driving pins being eccentrically mounted uponone of said rotatable pinions, a ring gear arranged to rotate withsaid'spider, and gears carried Whenever it is desired to accuratelyfinish u by said rotatable head which engage the ring gear and saidpinions and cause the work cage to movethrough a composite motion ofrotation and gyration.

2. A lapping machine having two horizontally opposed rotatable annularlaps of bonded abrasive grains, and a rotatable work cage interposedtherebetween which is arranged to move a multiplicity of work piecesbetween the opposed lapping faces, means for freely supporting the upperlap whereby it may accommodate itself to the top work surfaces, meansfor maintaining the cage operatively associated with the laps but out ofabrading contact therewith, mechanism to rotate said laps at high speedsin opposite directions, the rates of which are slightly different, andmeans to gyrate the work cage rapidly while causing it to rotate veryslowly at a speed approximately half the difference between the speedsof the laps and in the direction of the faster rotating lap, wherebyeach'work piece will be caused to follow an ever-changing path and movethrough a combined rotation and rapid sliding motion over the entireoperative surface of both of the opposed laps.

3. A lapping machine comprising tWo horizontally opposed rotatableconcentric laps of bonded abrasive grains and a freely rotatable workcage eccentrically mounted relative to the laps and arrangedto maintainamultiplicity of work pieces interposed therebetween, mechanism torotate both laps rapidly in opposite directions and at slightlydifferent rates, means for freely supporting the upper rotatable lapwhereby said lap may accommodate itself to the top work surfaces, meansto support the work cage out of contact with both laps and mechanismassociated with the lap rotating means adapted to revolve the I workcage center rapidly about the axis of the laps and cause the work piecesto slide axially at a rapid rate as they roll rapidly along aprogressively changing path over the entire surface of both of theopposed rotating lap faces, the work cage being rotated slowly about itsaxis whereby the centrifugal force acting axially on the work pieces isminimized.

Signed at Worcester, Massachusetts, this 18th day of July, 1930.

, HERBERT S. INDGE.

